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Sky in Gamma-Ray

NASA's Fermi Gamma-ray Space Telescope has unveiled a previously unseen gamma-ray structure centered in the Milky Way. The feature extends 25,000 light-years north and south of the galactic center and may be the remnant of an eruption from a supersized black hole at the center of our galaxy.

Scientists now are conducting more analyses to better understand how the never-before-seen structure was formed. The bubble emissions are much more energetic than the gamma-ray fog seen elsewhere in the Milky Way. The bubbles also appear to have well-defined edges. The structure's shape and emissions suggest it was formed as a result of a large and relatively rapid energy release, the source of which remains a mystery.

One possibility includes a particle jet from the supermassive black hole at the galactic center. In many other galaxies, astronomers see fast particle jets powered by matter falling toward a central black hole. While there is no evidence the Milky Way's black hole has such a jet today, it may have in the past. The bubbles also may have formed as a result of gas outflows from a burst of star formation, perhaps the one that produced many massive star clusters in the Milky Way's center several million years ago.

"In other galaxies, we see that starbursts can drive enormous gas outflows," said David Spergel, a scientist at Princeton University in New Jersey. "Whatever the energy source behind these huge bubbles may be, it is connected to many deep questions in astrophysics."

Fermi scans the entire sky every three hours, and as the mission continues and our exposure deepens, scientists see the extreme universe in progressively greater detail.

Click here to see a higher-resolution but less-sensitive record of the gamma-ray sky.

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